Paraganglioma-like Dermal Melanocytic Tumor
David S. Cassarino, MD, PhD
Cyril Fisher, MD, DSc, FRCPath
Key Facts
Terminology
Paraganglioma-like dermal melanocytic tumor (PDMT)
Rare dermal-based, low-grade melanocytic tumor with histologic similarities to paraganglioma
Microscopic Pathology
Typically composed of packets of oval to spindleshaped cells surrounded by thin fibrous septa
Uniform nuclei, small nucleoli, clear cytoplasm
Ancillary Tests
Positive for S100 protein, Melan-A and HMB-45 (variable)
Top Differential Diagnoses
Clear cell/balloon cell melanoma
Clear cell sarcoma
Perivascular epithelioid cell tumor (PEComa)
Primary dermal melanoma
 Histologic section shows a diffuse proliferation of clear cells located in the dermis. PDMTs are often a wellcircumscribed but unencapsulated, dermal-based tumor that can extend into the subcutis. |
 The tumor is composed of closely packed nests of cells with clear or granular cytoplasm and round to oval nuclei with small nucleoli  . |
TERMINOLOGY
Abbreviations
Paraganglioma-like dermal melanocytic tumor (PDMT)
Definitions
Dermal-based low-grade melanocytic tumor with histologic similarities to paraganglioma
CLINICAL ISSUES
Epidemiology
Incidence
Very rare tumors; only 10 cases reported to date
Age
Typically occurs in young adults
Range: 18-53 years
Mean: 35 years
Gender
More common in females
Site
Usually on extremities
Mostly lower limb
Thigh, knee, lower leg
Presentation
Dermal-based lesion
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